Tuning mechanism for radio receiving sets



April 22, 1941. A. s. WELLS TUNING MECHANISM FOR RADIO RECEIVING SETSOriginal Filed April 25, 1938 3 Sheets-Sheet l 14 [barf xii l April1941- A. s. WELLS 2,239,067

TUNING MECHANISM FOR RADIO RECEIVING SETS Original Filed April 25, 19383 Sheets-Sheet 2 INVENTOR.

4/6er2 J W /5 BY g r April 22, 1941. A. s. WELLS 2,239,057

TUNING MECHANISM FOR RADIO RECEIVING SETS Original Filed April 25, 19383 Sheets-Sheet 3 IN VENTOR.

Patented Apr. 22, 1941 TUNING MECHANISM FOR RADIO RECEIVING SETS AlbertS. Wells, Chicago, 111., assignor to Wells- Gardner & Company, Chicago,Ill., a corporation of Illinois Original application April 25, 1938,Serial No.

Divided and this application September 26, 1940, Serial No. 358,499

7 Claims.

It is a primary object of this invention to provide a simple andefficient means for tuning a radio set into resonance with a desiredstation by operation of a selected manual. The mechanism employed forthis purpose, as hereinafter disclosed, may be quickly and readilypre-set for a number of selected stations, enabling the user to tune inwith any one of said stations by operation of a single manual. Theoperating connections may include a series of driving manuals eachmovable toward and from an eccentrically rotatable shaft on which ismounted a plurality of cams or arms one of which is adapted to be drivenby each manual through the exertion of an operating force which proceedswith special mechanical advantage, all as hereinafter set forth.

The improvements which characterize this invention have been previouslydisclosed in my Patent No. 2,214,785, dated September 17, 1940, of whichthis case is a division. More particularly, these improvements have todo with certain elements mounted upon a common shaft adapted tocooperate selectively with the manuals by which the tuning operationsare carried out, these elements presenting various advantages in thedirections of simplicity, economy and dependability, all as fullydescribed in the following specification and shown in the accompan ingdrawings in the manner following:

Figure l is a partial vertical section on line I-| of Fig. 2, showingone of the manual-cam assemblies comprised in the present mechanism;

Fig. 2 is a vertical section through the tuning mechanism assembly,taken on line 22 of Fig. 1, one of the tuning levers being shown asdepressed while the others are in normally raised position;

Figs. 3, 4, and 5 are fragmentary sections on lines 3-3, 4-4, 55,respectively, of Fig. 2;

Fig, 6 is an end elevation, looking in the direction indicated by thearrows on line 6-6 of Fig. 2;

Figs. 7 and 8 are diagrammatic views illustrating the relationship ofone of the manuals to its associated heart cam at two extreme positionsof the latter;

Fig. 9, which is a view similar to Fig. 1, taken on line 9--9 of Fig.10, shows a modified construction in which arms are substituted for camson the operating shaft; and

Fig. 10 is a fragmentary top plan View of the mechanism shown in Fig. 9.

The mechanism illustrated in Figs. 1 to 8 comprises a radio chassisframe A in which is mounted a tuning shaft B (with which are associatedappropriate condensers or other tuning elements) and an operating shaftC fixed eccentrically in journals I4 and I5 which are suitably mountedto rotate in bearings l6 and Il, respectively. The latter of thesebearings may be carried by a closure plate l8 affixed over a largeopening in one end of the chassis frame; when this plate is removed,insertion and removal of the tuning mechanism, as a unit, may beaccomplished with ease. A key-way [9 extends lengthwise of the shaftwhich at one end is serrated as at 20 to facilitate a driving connectionwith the journal l5 whereto it is fitted.

Upon the shaft are affixed a plurality of elements, each adapted to bedriven in response to operation of a manual, as hereinafter explained.As shown in Figs. 1 to 8, each such element may be in the form of aheart cam D made up desirably of two similar complementary plates 2| and22 in adjacent relation. Both cam plates are apertured to receive theshaft, and at a short distance therefromare pivotally connected as bymeans of a boss 23 extruded from one face of each plate to produce uponits opposite face a corresponding recess 24. By facing two adjacent camplates in the same direction, the boss of one will enter the recess ofthe other to provide a pivotal connection therebetween. The plates ofeach cam are provided with registering slots 25 located on the shaftside opposite their pivotal interconnection and at a distance from theshaft which is relatively great; and at opposite ends of each slot arealigned lugs 26 over which are fitted the ends of compression springs 21whose axes are disposed transversely to a line in intersection with theshaft axis and pivotal axis between the cam plates. With the spring setin place, a tension is thereby exerted against the two plates of thecam, causing them to engage tightly with the operating shaft so as to befrictionally locked against rotation with respect thereto.

On each side of each pair of cam plates I may place a friction washer2'8 (see Fig. l) having a tongue 29 which extends into the key-way so asto lock the washer with the shaft at all times. Spacers 30 may also beplaced between each of these sets of friction Washers.

At one end of the operating shaft is secured a wa her 3i to lock theshaft of the journal l5. To the opposite end of the shaft is aflixed adrum 32 concentric with the journal [4 which is formed with a hub 33through which the shaft extends. Beyond this hub is located a pair ofrelatively rotatable complementary cam disks 34 and 35 which are mountedon the operating shaft; these cam disks may be secured on the shaft asby means of a nut 36 and lock washer 31 having a tongue disposed withinthe shaft keyway and an ear 38 engaging the nut to prevent rotationthereof after it is once adjusta'bly secured in place. The coacting camdisks are formed on their facing sides with complementary beveledsurfaces 39, and one of these disks is provided With a tongue extendinginto the keyway to lock therewith, the other disk being free to rotateupon the shaft. When the high and low portions of the beveled surfaceson the two cam disks coincide, there is an absence of pres sure endwiseon the shaft, but by turning one of these disks relative to the other anendwise pressure is exerted along the shaft through the hub 33, thejournal I4, the washers 28 and the spacers 3.6, to lock the severalpairs of cam plates fixedly to the shaft in any selected rotativeposition thereupon. With the cam disks manipulated to relax pressurelengthwise of the shaft, ready adjustment of each heart cam separatelywill be facilitated.

The range of movement of the operating shaft, say 180, may be fixed asby an arm 4! secured to the journal I which engages at either end of theshaft oscillation with a finger 42 which may be conveniently struck outfrom the closure plate I8. The arm 4! is also formed with opposedextensions 43 (Figs. 2 and 3) adapted to be connected as by screws 44 tothe ends of a flexible driving disk 45 which is suitably connected toone end of the tuning shaft.

The journal i4 is prevented from turning about the shaft as by a washer45 (partly shown in Fig. 5) which is similar to a second washer 41. Thislatter washer is formed with an inwardly extending lug 48 which passesthrough a slot in the end of the drum hub 33 and into the shaft key-wayl9, thereby locking the hub to the shaft. The washer 46 has a similarinwardly extending lug which looks the journal M to the shaft. A spring49 (Fig. 5) serves to press the washers 46 and 41 apart so as to preventany backlash.

Each of the friction washers 28 is provided with a pair of shoulders 50and 5! spaced apart something more than 180 (Figs. 1 and 4), eachadapted to engage in turn an ear 52 which is outwardly struck from oneof the cam plates 2| and 22 whereby to limit the adjustment of the heartcams to 180 or thereabouts. The heart cams may be actuated in eachinstance by a follower roller 55 which is mounted to move through afixed path in response to operation of a manual E. In the drawings eachmanual is represented as a lever 55 hingedly mounted upon a fulcrum rod51, the manual being normally maintained away from the cam as by aspring 58. Buttons 59, marked with the call letters of the station towhich it corresponds, may be affixed to the outer ends of these manualswhich are extended through slots 66 in the front wall of the chassisframe. To operate, the manual corresponding to the station desired isdepressed thereby causing the follower roller to turn its associatedheart cam to rotate the operating shaft; this movement continues untilthe roller has advanced as far as possible toward the shaft whichposition is reached when the roller lies in the notch opposite the pointof the heart cam. By so proceeding, accurate tuning maybe performedprovided that the cam itself has been pre-set properly on the operatingshaft.

The drum 32 may be driven by a cord 6| which is wound around a shaft 62to which is connected a suitable knob, not shown. The drum carries asheave 63 (Fig. 2) about which passes a cord 64 passing over suitablepulleys 65, B6, B1 and 68 to connect with an indicator 69 which movesacross a scale to indicate the position of the tuning condenser. Thisscale may be graduated in any suitable units, or it may carry the namesof the stations to which the set may be tuned.

The method of adjusting one of the heart cams for a given station may beas follows: The operator first manipulates the coacting cam disks 34 and35 so as to relax the pressure endwise of the operating shaft. The setis then very accurately tuned by hand into resonance with a desiredstation. The heart cam representing this station may be adjusted bypressing the manual as far as it will go, the operatingshaft meantimebeing held from rotation. This is easy of accomplishment because, whenthe cam disks are released, there is no endwise pressure exerted uponthe several cams and they are accordingly free, in response to arotative force sufficient to overcome their frictional engagement withthe shaft, to take up new adjusted positions thereupon. Pressure uponone of the manuals may sufiice to complete for the associated cam thisadjustment which thereupon becomes very exact and accurate. Theremaining heart cams, however, need not be disturbed since each retainsits frictional locking engagement with the operating shaft. Each heartcam may, in turn, be adjusted in the same Way. With these adjustmentsmade, the cam disks are turned back to locking position whereby all ofthe heart cams are subjected to endwise pressure and thereby firmlylocked once more to the operating shaft.

In Figs. 9 and 10 is shown a modification in which condensers 10 aremounted on a tuning shaft F to which is affixed a worm wheel H meshingwith a worm 12, the latter being carried fast on an operating shaft Gwhich is rotatably supported in bearings 13 (one only being shown)mounted on the chassis frame H. The operating shaft to the inside ofeach bearing is offset slightly, as at M, this portion of the shaftbeing adapted to receive a plurality of driven elements I, here shown asarms, each having a roller 15 rotatably mounted thereon. These severalarms are held fast between friction washers 16 with intervening spacersH, as already described in connection with Fig. 2. Means similar to thatpreviously described may be used for providing or releasing an endwisethrust along the operating shaft so as to permit each of the arms to beadjusted rotatively upon the shaft for purposes and in the manner whichhas been previously described connection with the heart shaped cams.

A series of manuals, here shown as levers J, one for each of the armrollers, are mounted for movement upon a longitudinal rod with spacers8i intervening to fix the manuals apart a desired distance. Each ofthese manuals extends over the operating shaft where it is formed with aslot 82 within which the shaft and proximate spacer may lie when themanual is depressed. At the entrance to this slot are opposed bearingpoints 33 and 84 spaced apart a distance slightly less than the diameterof th arm roller with which these points are adapted to coact. Forconvenience, each manual is equipped at its outer end with a button 85on which may be displayed the call letters of a desired station to whichthe parts associated with this lever may be adjusted. By applyingpressure to one of these buttons, the associated lever is moved to swingto its lowest position the roller on the proximate arm thereby rotatingthe operating and tuning shafts to the exact point required for placingof the condensers in resonance with the station selected. These severalmanuals may be permitted to ride up and down on the rollers, or each maybe held up by a separate spring if so desired.

According to Figs. 1 and 2, the operating shaft is mounted eccentricallyin journals which, when rotated, cause the shaft axis to move through anare instead of remaining fixed in accordance with usual practice. Thesame result follows in the construction of Figs. 9 and 10 wherein theshaft which is offset intermediately of its ends is rotatedeceentrically in consequence. The effect in both cases is the same, via,the centers of the cams or arms with which the manuals coact, when inextreme positions, lie upon opposite sides of the shaft axis whichshifts laterally as indicated best in Figs. 7 and 8. Ln the extremeposition of Fig. "I, the manual engages the cam at a point which isoff-center with respect to its axis. An initial mechanical advantage isthereby obtained which reduces the effort necessary for startingrotation of the shaft.

I claim:

1. In apparatus of the class described, a tuning mechanism comprising arotatable shaft, a plurality of rotatively adjustable driven elementsmounted on the shaft, a common means for releasably locking all thedriven elements with respect to the shaft, a separate tension means inconnection with each driven element acting to apply therethrough aconstant force proceeding transversely against the shaft to provide foreach such element a friction lock operating independently of the commonlocking means aforesaid, and means engageable with each driven elementto cause relative rotation between the associated element and the shaftwhen the common locking means is released whereby to facilitate a newsetting of the driven element relative to the shaft.

2. In apparatus of the class described, a tuning mechanism comprising arotatable shaft, a plurality of driven elements spaced along the shaft,

tension means associated with each driven element acting to applytherethrough a constant force proceeding transversely against the shaftto provide a friction lock for such element, a series of operatingmanuals, one for each driven element, and means. operable withindependence of the several friction locks, for locking all drivenelements to the shaft so that with the locking means released eachelement can be adjusted rotatively with respect to the shaft by means ofits manual and with the locking means set the shaft can be turned to aposition corresponding to any one of the driven. elements by means ofits manual.

3. In apparatus of the class described, a tuning mechanism comprising arotatable shaft, a

plurality of driven elements spaced along the shaft, tension meansassociated with each driven element acting to apply therethrough aconstant force proceeding transversely against the shaft to provide afriction lock for such element, a series of operating manuals, one foreach driven element, and means located at one end of the shaft, operablewith independence of the several friction locks, for locking all drivenelements to the shaft so that with the locking means released eachdriven element can be adjusted rotatively with respect to the shaft bymeans of its manual and with the locking means set the shaft can beturned to a position corresponding to any one of the driven elements bymeans of its manual.

4. In apparatus of the class described, a tuning mechanism comprising arotatable shaft, a plurality of heart cams spaced along the shaft, eachcam being composed of two similar sections pivotally connected at oneside of the shaft and having spring means for causing them to engage theshaft whereby to frictio-nally lock therewith, a series of operatingmanuals, one for each cam, and means, operating with independence of theseveral spring friction locking means, for firmly looking all cams tothe shaft so that with the locking means released each cam can beadjusted rotatively with respect to the shaft by means of its operatingmanual and with the locking means set the shaft can be turned to aposition corresponding to any one of the cams by means of its manual.

5. For use with a shaft in connection with tuning condensers, a manual,and a cam on the shaft engageable by the manual, the cam comprising twocomplementary plates having registering apertures through which theshaft is extended, a pivotal connection between the plates at one sideof the shaft, and a spring exerting a tension between the plates at anopposite side of the shaft whereby to urge the plates to swing abouttheir pivotal connection with a consequent frictional engagement withthe shaft.

6. For use with a shaft in connection with tuning condensers, a manual,and a cam on the shaft engageable by the manual, the cam comprising twocomplementary plates pivotally connected at a fulcrum point inengagement with opposite sides of the shaft at a weight point, andspring means acting on the plates at a power point to exert a leverageupon the shaft whereby to frictionally lock the cam against rotationrelative thereto.

7. For use with a shaft in connection with tuning condensers, a manual,and a cam on the shaft engageable by the manual, the cam comprising twoadjacent complementary plates having registering openings through whichthe shaft is extended, each plate having a boss extended laterally fromone side and a corresponding recess on the other side, the boss of oneplate being entered into the recess of the other plate to provide apivotal connection therebetween, and spring means exerting a tensionbetween the plates such as to urge the plates to swing about theirpivotal connection with a consequent frictional engagement with oppositesides of the shaft.

ALBERT S. WELLS.

